Protractor



Patented Mar. 10, 1925.

UNITED STATES- FREDERICKYH. BEULWITZ, OFCHICAGO, ILLINOIS;

rRoTRAcroR.

` Application mea July 2,

To all. whom t may concern.' n

Be 1t known that I, FREDERICK H. BEUL- WITZ, a citizen of the United States, resid.-

Ving at Chicago, in the county of Cook and 'State of Illinois, have invented a new and useful Improvement in Irotractors, of which the following is a specification.

This invention relates to a device for dil 4viding circles, laying out angles and the like and is fully described in the following spec-ification and shown in the accompanying drawings in which:

Figure 1 is ak top plan Vview of the' device, Fig. 2 is a bottom plan view of the same, Fig. 3 is an enlarged section on the line 3 of Fig. 1, and Fig. 4 is a section on linev 4 of Fig. 3. l p

The device as illustrated comprises a plate 10 which is preferably circular and has Va central threaded post 11 secured thereto. AA disk l2 somewhat smaller than the plate 10 is accurately journaled upon the post 11 and is adjustably secured thereto by means of a nut 13 which is screwed down over the threaded portion ofthe post 11.

The post llhas a central longitudinal hole 14 in which is fitted a pin 15. This pin eX- tends up through the top of the post which is provided with a series of slots 16 and is threaded and tapered to receive the nut 17. By tightening this nut the pin 15 may be secured in any adjusted position.

The circular plate 10 as illustrated is divided into forty equal spaces, the zero point 18 of this scale lies adjacent the lug 19 which is spaced a short distance from the Zero point the purpose of which will later be explained. The disk 12 has a scale covering six tenths of its circumference, this space being divided into twenty-tive equalV parts so that each of these parts represent .024 of a circle. It will be observed that the spaces on the lower plate represents a fortieth of a circle or .025. The spaces of the two circles consequently differing by one thousandth part of a circle providing a vernier which will be readily understood. Y Y

An arm 20 is fitted upon a shoulder 21 von the lower face of the nut 13 so that this arm can readily be moved even when the nut 13 is tightly set upon the disk 12.

This arm carries a block 22 at its outer end which is adapted to swing into contact with the lug 19. iThis block has a pin 23 which has a good running fit in the. opening 24 in the exact center in the block 22,

1923. serial No. 649,001.

the block 22 being of a thickness te' talig the pin 23 exactly on afradial line throughY the zero point in the outer scale. This pinA is carried by a knob 25 Vwhich is lheldfin place by a gripping nut26. This knob is carried by a spring27 which issecured tol the ar1n20. The pin 23 is adjustably held by the nut 26 over the plane of the bottom of the member lO. l

A lug 28 is carried yby the disk4 12 and has an edge 29 projecting beyond' the pev riphery yof the plate 10this Vedge being spaced back of the zero line ofthe scale on I j i the disk a distance equal to yone-half the thickness of the block 22.

To divideV a circle into any numberfof ed, each part is reduced to a Vdecimal and to represent this decimal. The pin 15l is vequal parts the fraction ofa circle represent-j` f l then placed in the center of the circle, vthe,l

plate 10 moved so that the Zerok point of 'the scalecoincides with one point of the cir` cle to be divided. The arm 2O is then moved so that the block -22`contacts`the lug 19 and the knob 25 depressed lso as fto cause'thepin 23 to punch a holel in the paper beneath. With the plate l() held in this position the lever is then moved so as to bring the block into contact with the lug 28 and the pin 23 is again depressed makingv av second small hole.

contact with' the -block 22, when` the plate 10 is again held and the arm20 moved until it again contacts the lug 28. ,The pin 23 is again depressed. l

This operation is then repeated l until the required number of divisionsv is made. By this arrangement the usual errors of dividing circles is avoided and greater acn curacy of dividing is obtained.

In setting the device it` .will be observed that as the zero point of the vdisk 12V reaches each of the-numbered divisions, the number opposite to whichl it is placed will be onetenth of a circle.v Each of the smaller divisions is one-fortieth of a circle or twentyfive thousandths.

dial scale and places that opposite `the corre p The pin 23 is held inl this position andthe plate 10 and disk 12jy rotated until the lug 19 again comes into f90 As has been explainedl each of thev smaller divisions vof the disk 12 Y sponding ininiberwof the nnitswoimthe oiiter` 'scale l It VWill be apparent that any angle may thus be laid out by first reducing it to a y -5 decimal part of the circle.

VLclain'i all noveltylinlierehtin Inyl invention 15 14A device rfor dividing circles corn@'ris-V V.a lug projecting from the edge of said plate, Y-tlie facngfedges of'saidlugs forming stops struction: 'and arrangeinent may l be ,made

v iS, .Stopped byeitherflng. as broadlyas poesiblein viewlof thefprior s1 ,eolienne lblock, said pin,beingfona'radialline','drawn y i ythrough the zero' pointTofeithergscale4when k oiintefdio swing-ftheblock is in eontact vvith either' li1g. pe having a 111g extending, over theedgepf said plate, said ,di'slbeing Eprovided' with a scale cooperating With said first scale to form a Vernier,

for marking the angular k'setting of the device, 'Said edges vbeing adjacent the zero point of said scales, apin point extending from the centerbf'the bottoni of the device, an arm movable about thel center of saidplate, ,and f a pin ,carried yby `Said arm adapted to'liebn a radial, line drawn through the, zeropoint v of either`- Scale when in ovedfs'o that` said arm ing a oircnlarplate.having'aecaleithereon j of said lngs,' and ,a 111,1', the center of 'Said 

